The pressure is mounting for a government-mandated ceiling on carbon emissions from cars.

Australia lags behind on emission control

Australia's car fleet remains one of the world's big polluters, with average carbon dioxide (CO2) emissions roughly 40 per cent worse than Europe and Japan.

Recently released figures show that the average CO2 output of a new passenger car sold in Australia is 197.5 grams of CO2 per kilometre, compared with 145.9g/km in Europe and 130g/km in Japan.

Some of that discrepancy can be traced to Europe's preference for diesel-powered passenger cars and the popularity of tiny "kei" cars in Japan but the rest is likely to be the result of Australians' long-standing love affair with large, thirsty cars.

While the comparison with Europe is unflattering, Australia still compares well with the US, which has an average CO2 output of 255g/km.

Prius

But the CO2 figures put pressure on the federal government to come up with a mandatory emissions target for vehicles, rather than the existing voluntary target.

The Department of Transport is believed to be leaning towards a mandatory target but any decision is some months away.

The department is about to release a regulatory impact statement (RIS) on the topic, responding to a working group recommendation for mandatory CO2 targets.

Europe has set an aggressive compulsory average CO2 output target of 120g/km by 2015. The US, Japan and China also have mandatory targets for reducing CO2 output for cars.

Australia's voluntary code, agreed between the Federal Chamber of Automotive Industries (FCAI) and the government, has drawn criticism from the Greens and environmental groups.

The Greens deputy leader, Senator Christine Milne, says the RIS is overdue and the government is dragging the chain on the issue of vehicle emissions in an attempt to protect the local car industry, which builds large six-cylinder sedans, utility vehicles and four-wheel-drives.

"Australians have the right to know, before the election, what the government plans to do to help them get more efficient cars in the face of rising oil prices, the climate crisis and peak oil. Is the government going to finally introduce mandatory vehicle fuel efficiency standards?" she says.

Milne claims the government is aiming at a "woeful" target of 195g/km by 2015, well short of overseas standards.

"This might be what car and oil companies want but it is no help to all those Australians facing rising oil prices and long commutes without convenient public transport alternatives," she says.

"Not only are emissions of the Australian car fleet far behind where they should be but cars manufactured in Australia perform particularly poorly.

"All of the cars manufactured locally have emissions far in excess of the industry's already-lax voluntary target. Australian manufacturers are building cars that Australians don't want.

"In 2007, only about a quarter of the cars made here were sold to private buyers - the rest went to government [many of whom are trying to support local manufacturers] and business fleets."

But a spokesman for the Department of Transport says the Greens' criticisms are "hypocritical" given their role in the scrapping of the carbon trading scheme.

"The criticism from the Greens is a bit rich given they voted with Tony Abbott's Liberals last December to block this government's efforts to put a price on carbon," he says.

The chief executive of the FCAI, Andrew McKellar, says the industry has "an open mind" about mandatory emission targets but argues the voluntary targets have worked well so far.

Meanwhile, stable fuel prices have seen fleet, government and private buyers flock back to thirsty 4WDs.

In the first five months of this year, sales of the biggest, thirstiest 4WDs in the market are up by more than 25 per cent, while Toyota's petrol-electric Prius is one of the few cars in Australia to record a drop in sales (down 22 per cent).

Sales of the Nissan Patrol are up 28 per cent, Toyota LandCruiser sales were up 27 per cent, Mitsubishi Pajero sales grew 67 per cent and Toyota Prado sales rose 53 per cent. Overall, sales of SUVs are up by a third this year.